26 DISEASES OF THE NASAL PASSAGES 



have been recorded, but in other countries (France, Germany) 

 they are frequently found. The Linguatula rhinaria are 

 white, the body lanceolated, elongated, vermiform and flat- 

 tened above and below, the ventral surface nearly plane, the 

 dorsal surface rounded, anterior extremity broad and rounded, 

 posterior extremity attenuated. The thorax is short and 

 between it and the abdomen there is no distinct boundary. 

 The integuments show about ninety rings or segments, widest 

 in their middle, causing the margins of the parasite to be 

 distinctly crenated. The hooks are sharp, curved, and bi- 

 articulated. Each hook is retractile into a small sheath and 

 is moved by muscular cords arranged in different direc- 

 tions. The mouth is rounded, digestive tube rectilinear. Size : 

 Male, 18-20 mm. long, 3 mm. broad in front and 0.5 mm. 

 behind. Female, 8-10 cm. long, 8-10 mm. broad in front 

 and 2 mm. behind. The eggs are ovoid, 90 mmm. long and 

 70 mmm. broad. 



The life cycle of the Linguatula rhinaria is as follows: 

 The female deposits her eggs in the nasal passages of the 

 dog; the eggs are expelled by sneezing and, being surrounded 

 by mucus, they adhere to grasses or whatever they happen 

 to come in contact with. The grasses are eaten by any of 

 the herbivorous animals. The shells of the eggs are dissolved 

 by the gastric juice and the embryos are set at liberty in the 

 intestinal tract. Each embryo is provided with a median 

 stylet and two curved hooks with which it penetrates 

 the walls of the intestines and reaches the peritoneum, 

 mesenteric glands, liver and the lungs where it becomes 

 encysted. During the period of encystment in the organs 

 and glands the embryo undergoes successive changes in its 

 development and becomes a larva (Linguatula denticulatum) . 

 When mature the larvae migrate by means of their hooks and 

 the sharp spiculte on their skin. Some of them pass into the 

 bronchi and trachea reaching the nasal passages where they 

 develop into the perfect parasite. Dogs become infested 

 by eating the viscera of animals containing the larval form 

 which passes from the stomach via the esophagus to the 

 nasal passages where it develops. 



